JP3782738B2 - Wastewater treatment method - Google Patents

Wastewater treatment method Download PDF

Info

Publication number
JP3782738B2
JP3782738B2 JP2002028473A JP2002028473A JP3782738B2 JP 3782738 B2 JP3782738 B2 JP 3782738B2 JP 2002028473 A JP2002028473 A JP 2002028473A JP 2002028473 A JP2002028473 A JP 2002028473A JP 3782738 B2 JP3782738 B2 JP 3782738B2
Authority
JP
Japan
Prior art keywords
concentration
supernatant
cod
biological filtration
tank
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP2002028473A
Other languages
Japanese (ja)
Other versions
JP2003225693A (en
Inventor
美子 宍戸
正信 小関
彰夫 中尾
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sumitomo Heavy Industries Ltd
Original Assignee
Sumitomo Heavy Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sumitomo Heavy Industries Ltd filed Critical Sumitomo Heavy Industries Ltd
Priority to JP2002028473A priority Critical patent/JP3782738B2/en
Publication of JP2003225693A publication Critical patent/JP2003225693A/en
Application granted granted Critical
Publication of JP3782738B2 publication Critical patent/JP3782738B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

Landscapes

  • Biological Treatment Of Waste Water (AREA)
  • Activated Sludge Processes (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、下水処理場等で用いられる排水処理方法に関する。
【０００２】
【従来技術】
多くの下水処理場では、下水を活性汚泥槽で好気処理して下水中の有機物を分解し、活性汚泥槽から排出される好気処理水を最終沈殿池に導入し、最終沈殿池において好気処理水中の汚泥を沈殿させ、最終沈殿池からの上澄液を河川等に放流している。
【０００３】
ところが、この上澄液には、未分解の有機物やアンモニア、毒性が高くＣＯＤを増加させる亜硝酸が含まれている。このため、上澄液をそのまま河川等に放流することは決して好ましいことではない。
【０００４】
そこで、通常、上澄液を生物ろ過槽で高度処理することにより、未分解の有機物やアンモニア、亜硝酸性窒素などの除去が図られている。このとき、生物ろ過槽における曝気量は通常、一定に保持される。
【０００５】
【発明が解決しようとする課題】
しかしながら、前述した従来の下水の処理方法は、以下に示す課題を有する。
【０００６】
即ち上記従来の下水の処理方法にあっては、下水の水質や活性汚泥槽における生物相のバランスがくずれることにより、活性汚泥処理で分解できなかった有機物が多量に生物ろ過槽に流入されることがある。この場合、生物ろ過槽において、曝気量が小さく且つ一定であると、その有機物の分解のために多量の酸素が必要となり、その結果、部分的に酸素取込みの競合、あるいは嫌気的な反応が起こり、生物ろ過槽に流入してきた亜硝酸性窒素濃度を低減できなくなる。また硝酸性窒素が亜硝酸性窒素となり、これが生物ろ過水に含有されたまま河川等に放流されることとなる。
【０００７】
本発明は、上記事情に鑑みてなされたものであり、生物ろ過水中の亜硝酸性窒素を十分低濃度にすることができる排水処理方法を提供することを目的とする。
【０００８】
【課題を解決するための手段】
上記課題を解決するため、本発明は、被処理排水を活性汚泥槽で好気処理する好気処理工程と、前記活性汚泥槽から排出される好気処理水中の汚泥を最終沈殿池で沈殿分離し、上澄液を排出する沈殿分離工程と、前記上澄液を生物ろ過槽で曝気しながら生物ろ過する生物ろ過工程とを含む排水処理方法であって、前記上澄液中のＣＯＤMn濃度及びＮＨ4−Ｎ濃度を測定し、これらの比を算出する算出工程と、前記ＣＯＤMn濃度及びＮＨ4−Ｎ濃度の比に応じて、前記生物ろ過槽における曝気量を制御する制御工程とを含むことを特徴とする。
【０００９】
この発明によれば、被処理排水が活性汚泥槽で好気処理され、活性汚泥槽から排出される好気処理水中の汚泥が最終沈殿池で沈殿分離されて上澄液が最終沈殿池から排出され、この上澄液が生物ろ過槽で曝気されながら生物ろ過される。このとき、被処理排水の水質や活性汚泥槽における生物相のバランスがくずれることにより、活性汚泥槽での好気処理で分解できなかった有機物が多量に生物ろ過槽に流入されることがある。この場合、生物ろ過槽において、その有機物の分解のために多量の酸素が必要となり、その結果、部分的に酸素取込みの競合、あるいは嫌気的な反応が起こり、生物ろ過槽に流入してきた亜硝酸性窒素濃度を低減できないことがある。また硝酸性窒素が亜硝酸性窒素となり、これが生物ろ過水に含有されたまま河川等に放流されることがある。また、本発明者等により、上澄液のＣＯＤMn濃度及びＮＨ4−Ｎ濃度の比と、生物ろ過槽から排出される生物ろ過水中の亜硝酸性窒素濃度との間には相関があることが分かっている。そこで、本発明では、上澄液のＣＯＤMn濃度及びＮＨ4−Ｎ濃度の比に応じて、生物ろ過槽における曝気量を制御することとしている。これにより、上澄液のＣＯＤMn濃度及びＮＨ4−Ｎ濃度の比によらず、生物ろ過水中の亜硝酸性窒素を十分低濃度にすることが可能となる。また上澄液のＣＯＤMn濃度及びＮＨ4−Ｎ濃度の比に応じて生物ろ過槽における曝気量を制御することで、曝気量を一定にする場合よりも生物ろ過槽での過剰な曝気を十分防止することが可能となる。
【００１０】
上記制御工程において、前記ＮＨ4−Ｎ濃度に対する前記ＣＯＤMn濃度の比が２以上であるときに、前記生物ろ過槽の槽内液中の溶存酸素濃度が設定値以上になるように前記生物ろ過槽における曝気量を制御することが好ましい。
【００１１】
前記ＮＨ4−Ｎ濃度に対する前記ＣＯＤMn濃度の比が２以上になると、生物ろ過槽の槽内液中の溶存酸素濃度が減少しはじめ、生物ろ過水中の亜硝酸性窒素が高くなる傾向がある。この場合に、生物ろ過槽の槽内液中の溶存酸素濃度が設定値以上になるように曝気量を制御することで、生物ろ過水中の亜硝酸性窒素を十分低濃度にすることが可能となる。
【００１２】
ここで、溶存酸素濃度の設定値が６ｍｇ／リットルであることが好ましい。溶存酸素濃度の設定値が６ｍｇ／リットル以上になると、生物ろ過水中の亜硝酸性窒素を確実且つ十分に低濃度にすることができる。
【００１３】
【発明の実施の形態】
以下、本発明の実施形態について詳細に説明する。
【００１４】
図１は、本発明の排水処理方法を実施する排水処理装置を示すフロー図である。図１に示すように、排水処理装置１は、下水（被処理排水）を好気処理する活性汚泥槽２を備える。活性汚泥槽２には、活性汚泥槽２の槽内液を曝気する散気管３が設けられ、散気管３にはブロワ４により空気が供給されるようになっている。なお、活性汚泥槽２の内部には、下水と空気との接触時間を長くする観点から、下水が蛇行して通過するように仕切が設けられてもよい。
【００１５】
活性汚泥槽２から排出される好気処理水は、最終沈殿池５に導入される。最終沈殿池５では汚泥が沈殿分離され、上澄液が得られる。沈殿分離された汚泥は、活性汚泥槽２における汚泥濃度の低減を防止する観点から、活性汚泥槽２に返送され、上澄液は最終沈殿池５から排出されて生物ろ過装置６に導入される。
【００１６】
生物ろ過装置６は、生物ろ過槽８を備えており、生物ろ過槽８の内部には、散気管９が配設され、散気管９は、空気供給管１０を介してブロワ１１に接続されている。また、生物ろ過槽８には、槽内液中の溶存酸素濃度（以下、「ＤＯ」という）を測定するＤＯ計１２が設けられている。なお、生物ろ過槽８には、ろ層１４が配設され、ろ層１４は、セラミックやアンスラサイト等の無機系ろ材のほか、プラスチックなどの有機系ろ材等で構成されている。
【００１７】
また排水処理装置１は、上澄液を採取し、上澄液中のＣＯＤMn濃度及びＮＨ4−Ｎ濃度を測定し、これらの比を算出する測定機器７を備える。
【００１８】
そして、測定機器７、ＤＯ計１２及びブロワ１１は、制御装置１３に電気的に接続されている。制御装置１３は、ＣＯＤMn濃度及びＮＨ4−Ｎ濃度の比と、ＤＯ計１２で測定されたＤＯ値とに基づいてブロワ１１の出力を制御するものである。
【００１９】
次に、上記排水処理装置１を用いた排水処理方法について説明する。
【００２０】
先ずブロワ４，１１を作動し、下水を活性汚泥槽２に導入する。活性汚泥槽２においては、散気管３より槽内液に空気を供給して下水の好気処理を行う（好気処理工程）。すると、下水中の窒素分を含む有機物が活性汚泥によりアンモニア性窒素に分解され、アンモニア性窒素が酸化されて硝酸性窒素又は亜硝酸性窒素に変換される。
【００２１】
活性汚泥槽２から排出される好気処理水は最終沈殿池５に導入される。最終沈殿池５では、汚泥が沈殿分離され、上澄液が得られる（沈殿分離工程）。
【００２２】
しかし、この上澄液には、未分解の有機物やアンモニア、毒性が高くＣＯＤを増加させる亜硝酸が含まれている。そこで、上記未分解の有機物やアンモニア、亜硝酸を除去すべく、この上澄液を最終沈殿池５から排出して生物ろ過装置６の生物ろ過槽８に導入する。生物ろ過槽８においては、ブロワ１１により、散気管９から上澄液に散気空気が供給される。従って、上澄液は、曝気されながらろ層を通過する。これにより上澄液の生物ろ過が行われる（生物ろ過工程）。
【００２３】
このとき、下水の水質や活性汚泥槽２における生物相のバランスがくずれることにより、活性汚泥処理で分解できなかった有機物が多量に生物ろ過槽８に流入されることがあり、この場合には、生物ろ過水中の亜硝酸性窒素濃度が増加することとなる。
【００２４】
図２は、最終沈殿池５から排出される上澄液中の亜硝酸性窒素濃度、及び生物ろ過槽８から排出される生物ろ過水中の亜硝酸性窒素濃度の経時変化の一例を示すグラフ、図３は、上澄液のＣＯＤMn濃度／ＮＨ4−Ｎ濃度比の経時変化の一例を示すグラフである。図２より、１１月付近及び８月付近で上澄液中の亜硝酸性窒素濃度の高い領域が存在する。このとき、生物ろ過水中の亜硝酸性窒素濃度は１１月付近で高い値を示すが、８月付近では低い値を示している。また図３より、上澄液におけるＣＯＤMn濃度／ＮＨ4−Ｎ濃度比は、１１月付近で高い値を示すが、８月付近では低い値を示している。本発明者等は、図２、図３の結果から、生物ろ過水中の亜硝酸性窒素濃度と上澄液のＣＯＤMn濃度／ＮＨ4−Ｎ濃度比との間に相関があるのではないかと考え、それらの関係を調べた。結果を図４に示す。図４より、上澄液中のＣＯＤMn濃度／ＮＨ4−Ｎ濃度比が、生物ろ過水中の亜硝酸性窒素濃度と相関を持つことが確認できる。
【００２５】
以上のことから、本発明者等は、生物ろ過水中の亜硝酸性窒素濃度が増加するのは、▲１▼上澄液中に、分解しやすい有機物の割合が多くなるため、微生物の酸素要求量が高くなり、一時的に酸素不足となって完全に硝化が進まないか、▲２▼生物ろ過槽の一部に嫌気ゾーンが形成され、硝酸性窒素が亜硝酸性窒素に還元されることに起因するものと考えた。
【００２６】
ここで、上記▲１▼、▲２▼より生物ろ過水中の亜硝酸性窒素濃度を低減するためには、生物ろ過槽８の槽内液中の亜硝酸性窒素について十分硝化を行うため、あるいは嫌気ゾーンを消滅させるために、曝気量を増加させればよいと考えられる。
【００２７】
そこで、本実施形態では、測定機器７でＣＯＤMn濃度及びＮＨ4−Ｎ濃度を測定してこれらの比を算出し（算出工程）、算出された濃度比の値に応じて、制御装置１３によりブロワ１１の出力を制御し、生物ろ過槽８における曝気量を調整することとしている（制御工程）。即ち、上澄液のＣＯＤMn濃度／ＮＨ4−Ｎ濃度比が高くなった場合には、生物ろ過水中の亜硝酸性窒素濃度が高くなると推測されるため、生物ろ過槽８において曝気量を増加させる。一方、上澄液のＣＯＤMn濃度／ＮＨ4−Ｎ濃度比が低くなった場合には、生物ろ過水中の亜硝酸性窒素濃度が低いものと推測されるため、生物ろ過槽８において曝気量を減少させる。
【００２８】
こうしてＣＯＤMn濃度及びＮＨ4−Ｎ濃度の比に応じて、生物ろ過槽８における曝気量を調整することにより、上澄液のＣＯＤMn濃度／ＮＨ4−Ｎ濃度比及び亜硝酸性窒素濃度によらず、生物ろ過水中の亜硝酸性窒素を十分低濃度にすることができる。また、上澄液のＣＯＤMn濃度／ＮＨ4−Ｎ濃度比に応じて、曝気量が増減されるため、生物ろ過槽８における過剰な曝気を十分防止でき、省電力化が可能となる。
【００２９】
このとき、ＣＯＤMn濃度／ＮＨ4−Ｎ濃度比が２以上になるときに、生物ろ過槽８の槽内液中のＤＯ値が設定値以上になるように生物ろ過槽８における曝気量を調節することが好ましい。
【００３０】
ＣＯＤMn濃度／ＮＨ4−Ｎ濃度の比が２以上になると、生物ろ過槽８の槽内液中のＤＯ値が減少しはじめ、生物ろ過水中の亜硝酸性窒素濃度が高くなる傾向がある。この場合に、生物ろ過槽８の槽内液中のＤＯ値が設定値以上になるように曝気量を制御することで、生物ろ過水中の亜硝酸性窒素を十分低濃度にすることが可能となる。
【００３１】
従って、具体的には、ＣＯＤMn濃度／ＮＨ4−Ｎ濃度比が２未満のときは、ブロワ１１を制御して曝気量を設定値未満とし、ＣＯＤMn濃度／ＮＨ4−Ｎ濃度比が２以上のときは、ブロワ１１を制御して曝気量を設定値以上にする。
【００３２】
ここで、ＤＯ計１２でモニタされるＤＯ値の設定値が６ｍｇ／リットルであることが好ましい。ＤＯ値の設定値が６ｍｇ／リットル以上になると、生物ろ過水中の亜硝酸性窒素を確実且つ十分に低濃度にすることができる。
【００３３】
なお、本発明は、前述した実施形態に限定されるものではない。例えば上記実施形態では、生物ろ過槽８における曝気量を制御するために、測定機器７及び制御装置１３を用いてブロワ１１を制御しているが、オペレータが、測定機器７及び制御装置１３を用いずに、上澄液を採取してＣＯＤMn濃度、ＮＨ4−Ｎ濃度を分析により測定した後、その濃度比に応じてブロワ１１の出力を制御するようにしてもよい。
【００３４】
また、上記実施形態では、測定機器７は、ＣＯＤMn濃度及びＮＨ4−Ｎ濃度を測定し、且つこれらの比の算出を行う機能を併有しているが、測定機器７は、ＣＯＤMn濃度及びＮＨ4−Ｎ濃度を測定する濃度測定計と、濃度測定計で測定されたＣＯＤMn濃度及びＮＨ4−Ｎ濃度に基づいてこれらの比を算出する演算装置とで構成されてもよい。
【００３５】
次に、本発明の内容を、実施例を用いて具体的に説明する。
【実施例】
（実施例１）
図１に示す排水処理装置１を用いて以下のようにして下水の処理を行った。
【００３６】
即ち先ず下水を活性汚泥槽２で好気処理し、好気処理水を最終沈殿池５に導入し、好気処理水中の汚泥を最終沈殿池５で沈殿させた。そして、このとき最終沈殿池で得られる上澄液を生物ろ過装置６の生物ろ過槽８に導入し、上澄液を曝気しながら生物ろ過し、生物ろ過水を得た。
【００３７】
また、生物ろ過装置６を長期間安定して運転できるようにするため、生物ろ過装置６のろ層の逆洗を３〜１０日に１回行った。逆洗条件は通常、空洗５分−併洗６分−水洗４分とし、上澄液の汚れやろ材へのＳＳ付着物が多く、洗浄を強化したいときは空洗５分−併洗８分−水洗４分とした。
【００３８】
なお、生物ろ過装置６の仕様（即ちろ材、ろ材寸法、ろ層厚、ろ過速度、通気風量、空洗時の空洗速度、併洗時の空洗速度及び水洗時の水洗速度）は、下記表１に示す通りとした。
【表１】

Figure 0003782738
【００３９】
下水の処理に際しては、上澄液中のＣＯＤMn濃度、ＮＨ4−Ｎ濃度、ＮＯ2−Ｎ濃度を下水道試験法に従って測定すると共に、生物ろ過装置６で得られた生物ろ過水について下水道試験法に従ってＮＯ2−Ｎ濃度を測定した。
【００４０】
上澄液中のＮＯ2−Ｎ濃度が３ｍｇ／リットル以上であってＣＯＤMn濃度／ＮＨ4−Ｎ濃度が２以上のときには、制御装置１３によりブロワ１１を制御して、ＤＯ計１２で測定されたＤＯ値が６ｍｇ／リットル以上となるように曝気量を調節し、それ以外のときには、ブロワ１１を制御してＤＯ値が２〜６ｍｇ／リットルとなるように曝気量を調節した。その結果、上澄液のＮＯ2−Ｎ濃度及びＣＯＤMn濃度／ＮＨ4−Ｎ濃度比によらず、生物ろ過水中のＮＯ2−Ｎを、十分低濃度にできることが分かった。
【００４１】
（比較例１）
ブロワ１１の出力を一定にした以外は実施例１と同様にして下水の処理を行った。
【００４２】
そして、実施例１と同様にして、上澄液中のＮＯ2−Ｎ濃度、上澄液中のＣＯＤMn濃度／ＮＨ4−Ｎ濃度、生物ろ過水中のＮＯ2−Ｎ濃度を測定し、ＮＯ2−Ｎ濃度及びＣＯＤMn濃度／ＮＨ4−Ｎ濃度を、測定した年月に対応してグラフ上にプロットした。結果を図５，図６に示す。なお、図５中、「◆」は上澄液中のＮＯ2−Ｎ濃度、「■」は、生物ろ過水中のＮＯ2−Ｎ濃度を表す。
【００４３】
図５、図６に示す結果より、上澄液におけるＣＯＤMn濃度／ＮＨ4−Ｎ濃度比が高くなったときに、曝気量を増加させないと、上澄液中のＮＯ2−Ｎ濃度及び上澄液におけるＣＯＤMn濃度／ＮＨ4−Ｎ濃度比がともに高くなったときに、生物ろ過水中のＮＯ2−Ｎ濃度が増加することがあることが分かった。
【００４４】
また、上澄液中のＮＯ2−Ｎ濃度が３ｍｇ／リットル以上でも、ＣＯＤMn濃度／ＮＨ4−Ｎ濃度が２未満では、生物ろ過水中のＮＯ2−Ｎ濃度は低いままであることが分かった。
【００４５】
なお、生物ろ過水中のＮＯ2−Ｎ濃度と上澄液中のＣＯＤMn濃度／ＮＨ4−Ｎ濃度との関係を調べた。結果を図７に示す。図７に示す結果より、生物ろ過水中のＮＯ2−Ｎ濃度の増加は、上澄液中のＣＯＤMn濃度／ＮＨ4−Ｎ濃度と相関があることが分かった。
【００４６】
【発明の効果】
以上説明したように本発明の排水処理方法によれば、上澄液のＮＯ2−Ｎ濃度及びＣＯＤMn濃度／ＮＨ4−Ｎ濃度比によらず、生物ろ過水中のＮＯ2−Ｎを、十分低濃度にできる。また、上澄液のＣＯＤMn濃度及びＮＨ4−Ｎ濃度比に応じて曝気量が制御されるため、生物ろ過槽における過剰な曝気を十分防止でき、省電力化が可能となる。
【図面の簡単な説明】
【図１】本発明の排水処理方法を実施する排水処理装置の一例を示すフロー図である。
【図２】上澄液及び生物ろ過水中の亜硝酸性窒素濃度の経時変化の一例を示すグラフである。
【図３】図２の上澄液におけるＣＯＤMn濃度／ＮＨ4−Ｎ濃度の経時変化の一例を示すグラフである。
【図４】図２のＣＯＤMn濃度／ＮＨ4−Ｎ濃度及び生物ろ過水中の亜硝酸性窒素濃度との関係を示すグラフである。
【図５】比較例１に係る上澄液及び生物ろ過水中の亜硝酸性窒素濃度の経時変化を示すグラフである。
【図６】比較例１に係るＣＯＤMn濃度／ＮＨ4−Ｎ濃度の経時変化を示すグラフである。
【図７】比較例１に係る生物ろ過水中の亜硝酸性窒素濃度と、ＣＯＤMn濃度／ＮＨ4−Ｎ濃度との関係を示すグラフである。
【符号の説明】
１…排水処理装置、２…活性汚泥槽、５…最終沈殿池、８…生物ろ過槽。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wastewater treatment method used in a sewage treatment plant or the like.
[0002]
[Prior art]
In many sewage treatment plants, sewage is aerobically treated in an activated sludge tank to decompose organic matter in the sewage, and aerobic treated water discharged from the activated sludge tank is introduced into the final sedimentation tank. The sludge in the treated air is settled and the supernatant from the final sedimentation basin is discharged into rivers.
[0003]
However, this supernatant contains undecomposed organic matter, ammonia, and nitrous acid, which is highly toxic and increases COD. For this reason, it is not preferable to discharge the supernatant as it is to a river or the like.
[0004]
Therefore, removal of undecomposed organic matter, ammonia, nitrite nitrogen, and the like is usually attempted by subjecting the supernatant to advanced treatment in a biological filtration tank. At this time, the amount of aeration in the biological filtration tank is usually kept constant.
[0005]
[Problems to be solved by the invention]
However, the conventional sewage treatment method described above has the following problems.
[0006]
That is, in the conventional sewage treatment method described above, a large amount of organic matter that could not be decomposed by the activated sludge treatment flows into the biological filtration tank due to the balance of the quality of the sewage and the biota in the activated sludge tank. There is. In this case, if the aeration amount is small and constant in the biological filtration tank, a large amount of oxygen is required for the decomposition of the organic matter, resulting in partial competition for oxygen uptake or anaerobic reaction. The nitrite nitrogen concentration that has flowed into the biological filtration tank cannot be reduced. In addition, nitrate nitrogen becomes nitrite nitrogen, which is discharged into rivers and the like while contained in biological filtered water.
[0007]
This invention is made | formed in view of the said situation, and it aims at providing the waste water treatment method which can make nitrite nitrogen in biological filtrate water low enough.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides an aerobic treatment step for aerobic treatment of treated wastewater in an activated sludge tank, and sludge in aerobic treated water discharged from the activated sludge tank is precipitated and separated in a final sedimentation tank A wastewater treatment method comprising a precipitation separation step of discharging the supernatant and a biological filtration step of performing biological filtration while aerating the supernatant in a biological filtration tank, wherein the COD Mn concentration in the supernatant And a calculation step of measuring the NH 4 —N concentration and calculating a ratio thereof, and a control step of controlling the aeration amount in the biological filtration tank according to the ratio of the COD Mn concentration and the NH 4 —N concentration. It is characterized by including.
[0009]
According to this invention, the wastewater to be treated is subjected to aerobic treatment in the activated sludge tank, the sludge in the aerobic treated water discharged from the activated sludge tank is precipitated and separated in the final sedimentation basin, and the supernatant is discharged from the final sedimentation basin. The supernatant is biofiltered while being aerated in a biofiltration tank. At this time, due to the loss of the quality of the wastewater to be treated and the balance of the biota in the activated sludge tank, a large amount of organic matter that could not be decomposed by the aerobic treatment in the activated sludge tank may flow into the biological filtration tank. In this case, a large amount of oxygen is required in the biological filtration tank to decompose the organic matter. As a result, competition for oxygen uptake or anaerobic reaction occurs partially, and nitrous acid that has flowed into the biological filtration tank. In some cases, the nitrogen concentration cannot be reduced. In addition, nitrate nitrogen becomes nitrite nitrogen, which may be discharged into rivers and the like while contained in biological filtered water. In addition, the inventors have found that there is a correlation between the ratio of the COD Mn concentration and NH 4 -N concentration in the supernatant and the concentration of nitrite nitrogen in the biological filtrate discharged from the biological filtration tank. I know. Therefore, in the present invention, the amount of aeration in the biological filtration tank is controlled in accordance with the ratio of the COD Mn concentration and the NH 4 —N concentration in the supernatant. Thereby, it becomes possible to make nitrite nitrogen in biological filtrate water sufficiently low regardless of the ratio of the COD Mn concentration and NH 4 —N concentration in the supernatant. In addition, by controlling the amount of aeration in the biological filtration tank according to the ratio of COD Mn concentration and NH 4 -N concentration in the supernatant, excess aeration in the biological filtration tank is more sufficient than when the amount of aeration is kept constant. It becomes possible to prevent.
[0010]
In the control step, when the ratio of the COD Mn concentration to the NH 4 -N concentration is 2 or more, the biological filtration is performed so that the dissolved oxygen concentration in the liquid in the biological filtration tank becomes a set value or more. It is preferable to control the amount of aeration in the tank.
[0011]
When the ratio of the COD Mn concentration to the NH 4 -N concentration is 2 or more, the dissolved oxygen concentration in the liquid in the biological filtration tank starts to decrease and the nitrite nitrogen in the biological filtered water tends to increase. . In this case, by controlling the amount of aeration so that the dissolved oxygen concentration in the liquid in the biological filtration tank is equal to or higher than the set value, the nitrite nitrogen in the biological filtered water can be made sufficiently low. Become.
[0012]
Here, the set value of the dissolved oxygen concentration is preferably 6 mg / liter. When the set value of the dissolved oxygen concentration is 6 mg / liter or more, the nitrite nitrogen in the biological filtered water can be reliably and sufficiently reduced.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0014]
FIG. 1 is a flowchart showing a wastewater treatment apparatus for carrying out the wastewater treatment method of the present invention. As shown in FIG. 1, the wastewater treatment apparatus 1 includes an activated sludge tank 2 that aerobically treats sewage (treated wastewater). The activated sludge tank 2 is provided with an air diffuser 3 for aeration of the liquid in the activated sludge tank 2, and air is supplied to the diffuser 3 by a blower 4. In addition, a partition may be provided inside the activated sludge tank 2 so that the sewage passes meandering from the viewpoint of extending the contact time between the sewage and the air.
[0015]
The aerobic treated water discharged from the activated sludge tank 2 is introduced into the final sedimentation tank 5. In the final sedimentation basin 5, sludge is settled and a supernatant is obtained. From the viewpoint of preventing the sludge concentration in the activated sludge tank 2 from being reduced, the precipitated and separated sludge is returned to the activated sludge tank 2, and the supernatant is discharged from the final sedimentation tank 5 and introduced into the biological filtration device 6. .
[0016]
The biological filtration device 6 includes a biological filtration tank 8, and an aeration pipe 9 is disposed inside the biological filtration tank 8, and the aeration pipe 9 is connected to the blower 11 via an air supply pipe 10. Yes. Further, the biological filtration tank 8 is provided with a DO meter 12 for measuring a dissolved oxygen concentration (hereinafter referred to as “DO”) in the liquid in the tank. The biological filtration tank 8 is provided with a filter layer 14, and the filter layer 14 is composed of an inorganic filter medium such as ceramic or anthracite, or an organic filter medium such as plastic.
[0017]
The wastewater treatment apparatus 1 includes a measuring device 7 that collects the supernatant, measures the COD Mn concentration and the NH 4 —N concentration in the supernatant, and calculates the ratio thereof.
[0018]
The measuring device 7, the DO meter 12, and the blower 11 are electrically connected to the control device 13. The control device 13 controls the output of the blower 11 based on the ratio between the COD Mn concentration and the NH 4 -N concentration and the DO value measured by the DO meter 12.
[0019]
Next, a wastewater treatment method using the wastewater treatment apparatus 1 will be described.
[0020]
First, the blowers 4 and 11 are operated to introduce sewage into the activated sludge tank 2. In the activated sludge tank 2, air is supplied from the air diffuser 3 to the liquid in the tank to perform aerobic treatment of sewage (aerobic treatment step). Then, the organic substance containing nitrogen content in the sewage is decomposed into ammonia nitrogen by the activated sludge, and the ammonia nitrogen is oxidized and converted into nitrate nitrogen or nitrite nitrogen.
[0021]
The aerobic treated water discharged from the activated sludge tank 2 is introduced into the final sedimentation tank 5. In the final sedimentation basin 5, sludge is separated and a supernatant is obtained (precipitation separation step).
[0022]
However, this supernatant contains undecomposed organic matter, ammonia, and nitrous acid, which is highly toxic and increases COD. Therefore, in order to remove the undecomposed organic matter, ammonia and nitrous acid, the supernatant is discharged from the final sedimentation basin 5 and introduced into the biological filtration tank 8 of the biological filtration device 6. In the biological filtration tank 8, diffused air is supplied from the diffuser tube 9 to the supernatant by the blower 11. Therefore, the supernatant liquid passes through the filter layer while being aerated. Thereby, biological filtration of the supernatant is performed (biological filtration step).
[0023]
At this time, due to the loss of the quality of sewage and the balance of biota in the activated sludge tank 2, a large amount of organic matter that could not be decomposed by the activated sludge treatment may flow into the biological filtration tank 8. The concentration of nitrite nitrogen in biological filtered water will increase.
[0024]
FIG. 2 is a graph showing an example of changes over time of the nitrite nitrogen concentration in the supernatant discharged from the final sedimentation basin 5 and the nitrite nitrogen concentration in the biological filtrate discharged from the biological filtration tank 8; FIG. 3 is a graph showing an example of temporal change in the COD Mn concentration / NH 4 —N concentration ratio of the supernatant. From FIG. 2, there are regions having a high nitrite nitrogen concentration in the supernatant around November and August. At this time, the nitrite nitrogen concentration in the biological filtered water shows a high value around November, but shows a low value around August. Further, from FIG. 3, the COD Mn concentration / NH 4 -N concentration ratio in the supernatant shows a high value in the vicinity of November but shows a low value in the vicinity of August. From the results shown in FIGS. 2 and 3, the present inventors have found that there is a correlation between the nitrite nitrogen concentration in the biological filtrate and the COD Mn concentration / NH 4 -N concentration ratio in the supernatant. I thought and investigated their relationship. The results are shown in FIG. From FIG. 4, it can be confirmed that the COD Mn concentration / NH 4 -N concentration ratio in the supernatant has a correlation with the nitrite nitrogen concentration in the biological filtrate.
[0025]
In view of the above, the present inventors have found that the increase in the concentration of nitrite nitrogen in biological filtered water is as follows: (1) The ratio of organic substances that are easily decomposed in the supernatant increases. The amount becomes high, oxygen temporarily becomes insufficient, and nitrification does not proceed completely. (2) Anaerobic zones are formed in part of the biological filtration tank, and nitrate nitrogen is reduced to nitrite nitrogen. It was thought to be caused by
[0026]
Here, in order to reduce the nitrite nitrogen concentration in the biological filtered water from the above (1) and (2), in order to sufficiently nitrify the nitrite nitrogen in the liquid in the biological filtration tank 8, or In order to eliminate the anaerobic zone, the amount of aeration should be increased.
[0027]
Therefore, in the present embodiment, the COD Mn concentration and the NH 4 —N concentration are measured by the measuring device 7 to calculate these ratios (calculation step), and according to the calculated concentration ratio value, by the control device 13. The output of the blower 11 is controlled to adjust the amount of aeration in the biological filtration tank 8 (control process). That is, when the COD Mn concentration / NH 4 -N concentration ratio of the supernatant is increased, it is presumed that the concentration of nitrite nitrogen in the biological filtered water is increased. Let On the other hand, when the COD Mn concentration / NH 4 -N concentration ratio of the supernatant is low, it is presumed that the concentration of nitrite nitrogen in the biological filtered water is low. Decrease.
[0028]
Thus, by adjusting the amount of aeration in the biological filtration tank 8 in accordance with the ratio of the COD Mn concentration and the NH 4 —N concentration, the COD Mn concentration / NH 4 —N concentration ratio and the nitrite nitrogen concentration of the supernatant are adjusted. Regardless, the nitrite nitrogen in the biological filtered water can be made sufficiently low. Moreover, since the amount of aeration is increased / decreased according to the COD Mn concentration / NH 4 —N concentration ratio of the supernatant, excessive aeration in the biological filtration tank 8 can be sufficiently prevented, and power saving can be achieved.
[0029]
At this time, when the COD Mn concentration / NH 4 -N concentration ratio becomes 2 or more, the amount of aeration in the biological filtration tank 8 is adjusted so that the DO value in the liquid in the biological filtration tank 8 becomes the set value or more. It is preferable to do.
[0030]
When the ratio of COD Mn concentration / NH 4 -N concentration is 2 or more, the DO value in the liquid in the biological filtration tank 8 starts to decrease, and the nitrite nitrogen concentration in the biological filtered water tends to increase. In this case, by controlling the amount of aeration so that the DO value in the liquid in the biological filtration tank 8 is equal to or higher than the set value, it is possible to sufficiently reduce the concentration of nitrite nitrogen in the biological filtered water. Become.
[0031]
Therefore, specifically, when the COD Mn concentration / NH 4 -N concentration ratio is less than 2, the blower 11 is controlled to make the aeration amount less than the set value, and the COD Mn concentration / NH 4 -N concentration ratio is 2 In the above case, the blower 11 is controlled so that the amount of aeration is greater than or equal to the set value.
[0032]
Here, it is preferable that the set value of the DO value monitored by the DO meter 12 is 6 mg / liter. When the set value of the DO value is 6 mg / liter or more, nitrite nitrogen in the biological filtered water can be reliably and sufficiently reduced in concentration.
[0033]
In addition, this invention is not limited to embodiment mentioned above. For example, in the above embodiment, the blower 11 is controlled using the measuring device 7 and the control device 13 in order to control the amount of aeration in the biological filtration tank 8, but the operator uses the measuring device 7 and the control device 13. without, COD Mn concentration was collected the supernatant, was measured by analyzing the NH 4 -N concentration, may be controlled the output of the blower 11 in accordance with the concentration ratio.
[0034]
In the above embodiment, the measuring device 7 measures the COD Mn concentration and NH 4 -N concentration, but and are having both a function to calculate the ratio of these, the measuring device 7, COD Mn concentration and a concentration measuring meter for measuring the NH 4 -N concentration, may be constituted by an arithmetic unit for calculating these ratios based on COD Mn concentration and NH 4 -N concentration measured in a concentration meter.
[0035]
Next, the contents of the present invention will be specifically described using examples.
【Example】
Example 1
The wastewater treatment apparatus 1 shown in FIG. 1 was used to treat sewage as follows.
[0036]
That is, first, sewage was aerobically treated in the activated sludge tank 2, aerobic treated water was introduced into the final sedimentation basin 5, and sludge in the aerobic treated water was precipitated in the final sedimentation basin 5. At this time, the supernatant obtained in the final sedimentation basin was introduced into the biological filtration tank 8 of the biological filtration device 6 and biologically filtered while the supernatant was aerated to obtain biological filtered water.
[0037]
Moreover, in order to be able to operate | move the biological filtration apparatus 6 stably for a long period, backwashing of the filter layer of the biological filtration apparatus 6 was performed once every 3 to 10 days. The condition of backwashing is usually 5 minutes for washing with water-6 minutes for washing together with 4 minutes for washing with water. If there is a lot of SS deposits on the supernatant and filter medium, and if you want to enhance washing, wash with water for 5 minutes-combined washing 8 Minute-water washing 4 minutes.
[0038]
The specifications of the biological filtration device 6 (namely, filter medium, filter medium size, filter layer thickness, filtration speed, air flow rate, air washing speed during air washing, air washing speed during simultaneous washing, and water washing speed during water washing) are as follows: As shown in Table 1.
[Table 1]
Figure 0003782738
[0039]
In the treatment of sewage, the COD Mn concentration, NH 4 -N concentration, and NO 2 -N concentration in the supernatant are measured according to the sewer test method, and the sewer test method is applied to the biofilter water obtained by the biofilter 6. The NO 2 —N concentration was measured according to
[0040]
When the NO 2 -N concentration in the supernatant is 3 mg / liter or more and the COD Mn concentration / NH 4 -N concentration is 2 or more, the blower 11 is controlled by the control device 13 and measured by the DO meter 12. The aeration amount was adjusted so that the DO value was 6 mg / liter or more. In other cases, the aeration amount was adjusted by controlling the blower 11 so that the DO value was 2-6 mg / liter. As a result, it was found that NO 2 —N in the biological filtrate can be made sufficiently low regardless of the NO 2 —N concentration and the COD Mn concentration / NH 4 —N concentration ratio of the supernatant.
[0041]
(Comparative Example 1)
Sewage treatment was performed in the same manner as in Example 1 except that the output of the blower 11 was kept constant.
[0042]
Then, in the same manner as in Example 1, NO 2 -N concentration in the supernatant, COD Mn concentration / NH 4 -N concentration in the supernatant, the NO 2 -N concentration of biological filtration water was measured, NO The 2- N concentration and COD Mn concentration / NH 4 -N concentration were plotted on the graph corresponding to the measured years. The results are shown in FIGS. In FIG. 5, “♦” represents the NO 2 —N concentration in the supernatant, and “■” represents the NO 2 —N concentration in the biological filtrate.
[0043]
5, from the results shown in FIG. 6, when it becomes higher COD Mn concentration / NH 4 -N concentration ratio in the supernatant, if not increase the aeration amount, NO in the supernatant 2 -N concentration and above It was found that when the COD Mn concentration / NH 4 -N concentration ratio in the supernatant increases, the NO 2 -N concentration in the biological filtrate may increase.
[0044]
Further, even in NO 2 -N concentration in the supernatant is 3 mg / liter or more, in less than 2 is COD Mn concentration / NH 4 -N concentration, found that biological NO 2 -N concentration of the filtered water remains low It was.
[0045]
In addition, the relationship between the NO 2 —N concentration in the biological filtrate and the COD Mn concentration / NH 4 —N concentration in the supernatant was examined. The results are shown in FIG. From the results shown in FIG. 7, it was found that the increase in NO 2 —N concentration in biological filtrate was correlated with COD Mn concentration / NH 4 —N concentration in the supernatant.
[0046]
【The invention's effect】
Above, according to the waste water treatment method of the present invention, as described, regardless of the NO 2 -N concentration and COD Mn concentration / NH 4 -N concentration ratio of the supernatant, the NO 2 -N of biological filtration water, sufficient Low concentration can be achieved. Moreover, since the amount of aeration is controlled according to the COD Mn concentration and NH 4 —N concentration ratio of the supernatant, excessive aeration in the biological filtration tank can be sufficiently prevented, and power saving can be achieved.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an example of a wastewater treatment apparatus for carrying out a wastewater treatment method of the present invention.
FIG. 2 is a graph showing an example of a change with time of the nitrite nitrogen concentration in the supernatant and biological filtrate.
3 is a graph showing an example of a change over time in COD Mn concentration / NH 4 —N concentration in the supernatant of FIG. 2. FIG.
4 is a graph showing the relationship between the COD Mn concentration / NH 4 —N concentration and the nitrite nitrogen concentration in biological filtered water in FIG. 2. FIG.
FIG. 5 is a graph showing changes with time in the concentration of nitrite nitrogen in the supernatant and biological filtrate according to Comparative Example 1;
6 is a graph showing changes with time in COD Mn concentration / NH 4 —N concentration according to Comparative Example 1. FIG.
7 is a graph showing the relationship between the concentration of nitrite nitrogen in biological filtered water according to Comparative Example 1 and the COD Mn concentration / NH 4 —N concentration. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Waste water treatment equipment, 2 ... Activated sludge tank, 5 ... Final sedimentation tank, 8 ... Biological filtration tank.

Claims (3)

被処理排水を活性汚泥槽で好気処理する好気処理工程と、
前記活性汚泥槽から排出される好気処理水中の汚泥を最終沈殿池で沈殿分離し、上澄液を排出する沈殿分離工程と、
前記上澄液を生物ろ過槽で曝気しながら生物ろ過する生物ろ過工程と、
を含む排水処理方法であって、
前記上澄液中のＣＯＤMn濃度及びＮＨ4−Ｎ濃度を測定し、これらの比を算出する算出工程と、
前記ＣＯＤMn濃度及びＮＨ4−Ｎ濃度の比に応じて、前記生物ろ過槽における曝気量を制御する制御工程と、
を含むことを特徴とする排水処理方法。An aerobic treatment process for aerobically treating the wastewater to be treated in an activated sludge tank;
Settling and separating the sludge in the aerobic treated water discharged from the activated sludge tank in a final settling basin, and discharging the supernatant;
A biological filtration step of performing biological filtration while aerating the supernatant in a biological filtration tank;
A wastewater treatment method comprising:
A calculation step of measuring the COD Mn concentration and NH 4 -N concentration in the supernatant and calculating a ratio thereof;
A control step of controlling the amount of aeration in the biological filtration tank according to the ratio of the COD Mn concentration and the NH 4 -N concentration;
The waste water treatment method characterized by including. 前記制御工程において、前記ＮＨ4−Ｎ濃度に対する前記ＣＯＤMn濃度の比が２以上であるときに、前記生物ろ過槽の槽内液中の溶存酸素濃度が設定値以上になるように前記生物ろ過槽における曝気量を制御することを特徴とする請求項１に記載の排水処理方法。In the control step, when the ratio of the COD Mn concentration to the NH 4 -N concentration is 2 or more, the biological filtration is performed so that the dissolved oxygen concentration in the liquid in the biological filtration tank becomes a set value or more. The waste water treatment method according to claim 1, wherein the amount of aeration in the tank is controlled. 前記設定値が６ｍｇ／リットルであることを特徴とする請求項２に記載の排水処理方法。The waste water treatment method according to claim 2, wherein the set value is 6 mg / liter.
JP2002028473A 2002-02-05 2002-02-05 Wastewater treatment method Expired - Fee Related JP3782738B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2002028473A JP3782738B2 (en) 2002-02-05 2002-02-05 Wastewater treatment method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002028473A JP3782738B2 (en) 2002-02-05 2002-02-05 Wastewater treatment method

Publications (2)

Publication Number Publication Date
JP2003225693A JP2003225693A (en) 2003-08-12
JP3782738B2 true JP3782738B2 (en) 2006-06-07

Family

ID=27749670

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2002028473A Expired - Fee Related JP3782738B2 (en) 2002-02-05 2002-02-05 Wastewater treatment method

Country Status (1)

Country Link
JP (1) JP3782738B2 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4832032B2 (en) * 2005-09-13 2011-12-07 中国電力株式会社 Waste water treatment method and waste water treatment equipment
JP5956372B2 (en) * 2013-03-22 2016-07-27 株式会社日立製作所 Water treatment apparatus and water treatment method
CN104199406B (en) * 2014-08-25 2017-01-25 长江水利委员会长江科学院 System and method for evidence obtaining in water body pollution-discharge cruise monitoring

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0717438Y2 (en) * 1990-01-12 1995-04-26 荏原インフイルコ株式会社 Organic wastewater treatment equipment
JPH04322799A (en) * 1991-04-23 1992-11-12 Ebara Infilco Co Ltd Method and device for treating oil-containing waste water
JPH05177197A (en) * 1991-12-27 1993-07-20 Fuji Photo Film Co Ltd Treatment process for waste water
JPH09314156A (en) * 1996-05-29 1997-12-09 Meidensha Corp Ozone treatment apparatus in which biological filter device is incorporated
JPH11347583A (en) * 1998-06-03 1999-12-21 Toshiba Corp Apparatus for highly treating sewage
JP3450719B2 (en) * 1998-08-12 2003-09-29 神鋼パンテツク株式会社 Biological treatment method and apparatus for organic wastewater
JP2000107787A (en) * 1998-10-07 2000-04-18 Mitsubishi Heavy Ind Ltd Method for treating wastewater
JP2003103296A (en) * 2001-09-28 2003-04-08 Hitachi Ltd Biological treatment apparatus
JP3961835B2 (en) * 2002-01-07 2007-08-22 株式会社東芝 Sewage treatment plant water quality controller

Also Published As

Publication number Publication date
JP2003225693A (en) 2003-08-12

Similar Documents

Publication Publication Date Title
JP2009522101A (en) Method and system for nitrifying and denitrifying sewage
JPH11285696A (en) Device and method for sewage treatment
JP3782738B2 (en) Wastewater treatment method
JPH09314156A (en) Ozone treatment apparatus in which biological filter device is incorporated
JP3377346B2 (en) Organic wastewater treatment method and apparatus
JPH0724492A (en) Method for controlling operation of activated sludge circulation change method
JP3677783B2 (en) Nitrification method
JPH07148496A (en) Method for controlling operation of modified process for circulation of activated sludge
JP2004097926A (en) Water treatment method and water treatment equipment
JP3807945B2 (en) Method and apparatus for treating organic wastewater
JP3608256B2 (en) Operation control method for circulating nitrification denitrification
JPH05192688A (en) Anaerobic-aerobic activated sludge treating device using buffer tank
JPH09174071A (en) Method for treating organic sewage and apparatus therefor
JP2000070989A (en) Method and apparatus removing nitrogen in waste water
JP2001314892A (en) Method for controlling denitrification apparatus of wastewater
JPS58146495A (en) Treatment of organic waste liquid
JP2673488B2 (en) Method and apparatus for treating organic wastewater
JPH05277475A (en) Treatment method for water containing organic substance
JP3303475B2 (en) Operation control method of activated sludge circulation method
JP2004237219A (en) Biological membrane filter apparatus and treatment method
JP3396985B2 (en) Wastewater nitrogen removal method and apparatus
JP3260575B2 (en) Control method of intermittent aeration type activated sludge method
JPH10323688A (en) Method for removing phosphorus in waste water
JP2006231206A (en) Waste water treatment method and equipment
JPH05317884A (en) Anaerobic-aerobic activated sludge treating device

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20040819

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20051220

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20060307

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20060310

R150 Certificate of patent or registration of utility model

Free format text: JAPANESE INTERMEDIATE CODE: R150

S111 Request for change of ownership or part of ownership

Free format text: JAPANESE INTERMEDIATE CODE: R313111

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20090317

Year of fee payment: 3

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20090317

Year of fee payment: 3

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20100317

Year of fee payment: 4

LAPS Cancellation because of no payment of annual fees